Improvement in grinding-mills



E. HARRISON. v

Grinding Mill.

Patented May 8, 1866. I

UNITED STATES PATENT OFFICE.

EDWARD HARRISON, OF NEW HAVEN, "CONNECTICUT.

IMPROVEMENT IN GRINDING-MILLS.

- Specification forming part of Letters Patent No. 54,535, dated May8,1866.

To all whom it may concern:

Be it known that I, EDWARD HARRISON, of New Haven, in the county of NewHaven and State of Connecticut, have invented anew and usefulImprovement in Millstones and other Grinding-Surfaces; and I do herebydeclare that the following is a full, clear, and exact descriptionthereof, which will enable others skilled in the art to, make and usethe same, reference being had to the accompanyingdrawings, forming apart of this specification, in which-- Figure 1 is a face view of amillstone provided with my invention. Fig. 2, a section of the same,taken in the line 00 a, Fig. 1. Fig. 3, a section of the same, taken inthe line y y, Fig. 1. y A

Similar letters of reference indicate like parts.

Millstoues, metal grinding-plates, and the generality of allgrinding-surfaces are provided withfurrows of greater-or less dimensionsto perform two important functions-to wit, crushing or breaking thesubstance to be ground by the act-ion of the edges of the furrows on onestone or plate passing over the edges of those on the other stone orplate, and to serve as channels to admit of the free passage of thesubstance through or between the stones. In order to perform good workit is essential that these furrows, especially the master or mainfurrows,be kept open thatis to say, sufficiently deep and angular attheir cutting or abradingedges; and in millstones this is effected byfrequent picking, the furrows, under the wear of the stones, gettingshallow at very short intervals. When, however, the fu'frows of metalgrinding-plates become shallow in consequence. of wear, there'hashitherto been no remedy but to cast the plates aside and substitute newones in their place.

My invention is designed to obviate the ne cessity of the frequentpicking of millstones, and also to admit of metal plates being kept inproper working order an indefinite period; and to this end it consistsin having the stones or plates formed with grooves or channels in placeswhere the furrows are required, and inserting in said grooves orchannels a filling composed of a material softer than the grinding stoneor plate, so that the face of the filling will have a tendency to wearequally as fast as the face of the stone or plate, and therefore causethe furrows to remain of a suitable depth.

.A represents a millstone in. which grooves or channels a are cut ormade, corresponding in position to the ordinary master or main furrows.(See Fig.1.) These grooves or channels are of rectangular form, and theymay be of any suitable depth and of a width corresponding to the widthof the furrows.

B represents a filling, which may be of hard wood, cement, or anysuitable material, and softer than the stone A. The faces of the fillingB are inclined in a transverse direc tion, as shown clearly in Fig. 3,corresponding to the bottoms of the ordinary furrows, the elevated sidesof the filling being flush with the face of the stone and the depressedsides some distance below, leaving a cutting or abradin g edge, I), atone side of the grooves or channels.

From this description it will be seen that the furrows will be kept openunder the wear of the stone, as the softness of the filling will causeit to wear equally as fast as the face of the stone, although, onaccount of being depressed or sunken out, subjected to as much frictionas the face of the stone, still its softness will cause it to be abradedequally as fast. a

The above description will answer for or apply to metal grinding-plates.The filling may be kept in the grooves or channels by friction only, orother means may be employed. Y

A modification of the improvement may be made by using a hard fillingand arranging the same with set-screws or other equivalent means, sothat it may be depressed in the grooves or channels from time to time,as the face of the stone or plate wears. Thus the labor and time ofpicking or opening the furrows of millstones will be avoided andmetal-grindin g-plates made. to last an indefinite period of time.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is

Providing the faces or grinding-surfaces of millstones, metal plates,850., with grooves or channels corresponding in position to the furrowsrequired for said surfaces, and having the grooves or channels providedwith a filling composed of a material softer than the stone or plate.

EDWARD HARRISON. Witnesses CHARLES B. CRAFT, E. S. ROWLAND.

